Breast carcinoma is the leading cause of cancer in women in the U.S. It is well known that if breast cancer is detected early and in situ, the survival rate is very high. However, if the cancer has spread regionally, the survival rate drops to 69%, while if distant metastases are present, the survival rate is only 18%. Early detection of breast tumors is therefore critical to the successful treatment of breast cancer. Fortunately, mammographic screening programs have shown that significant reduction in the breast cancer mortality rate (30 to 50%) can be achieved through early detection of breast carcinoma. X-ray mammography is the only imaging modality with a proven capability for detecting early stage, clinically occult breast cancer. High quality mammography requires both excellent spatial resolution and high contrast. Previous investigators have analyzed the performance of state-of-the-art film-screen mammography systems and determined that they are limited in their ability to display structures of low contrast, typical of mammary tumors and microcalcifications. In view of the limitations in the existing detectors, we propose to investigate a direct detection approach in which the incoming X-rays are imaged using a X-ray sensitive photoconductor, lead iodide (Pbl/2). This photoconductor is coated over a readout matrix that has been developed recently using standard silicon CMOS methods commonly employed in integrated circuits. Mammography and other medical imaging, non-destructive testing, astronomy, diffraction. high energy physics.